phyCORE-ADuC812 QuickStart Instructions
54
© PHYTEC Meßtechnik GmbH 2002 L-462e_2
At this point you have created a project called Debug.uv2, consisting
of a C source file called Debug.c and the assembler file Startup.a51.
4.2.2
Setting Options for Target
When setting the memory configuration, the memory layout necessary
for the monitor must be taken into consideration.
The standard 8051 controller uses a Harvard memory architecture. In
this architecture, access to CODE and XDATA memory space goes to
physically different memory devices. Normally, for access to CODE
space, a non-volatile memory is utilized, i.e. ROM or Flash. For
access to XDATA space, a RAM is used. Using this memory model
with an 8051 derivative allows access to up to 64 kByte of memory
for CODE and 64 kByte for XDATA.
When debugging with the Keil monitor, it is important that the user
program (CODE) can be changed during runtime (e.g. to enable
setting of breakpoints). This requires the user program to be stored in
RAM and not in Flash. In order to ensure that the user program is
running in RAM, the monitor automatically configures a von
Neumann memory architecture in the address range 0000H-DFFFH
after reset. Here, in contrast to the Harvard architecture, access to
CODE and XDATA space is directed towards the same physical
memory device, normally RAM. With this von Neumann memory
architecture, it is now possible to change the application program
during runtime.
